Process for recovering benzene and fuel gas in an aromatics complex

Abstract

A process for separating xylene from a feedstock in which the feedstock is separated into a xylene stream, a benzene rich stream and a light ends stream. Two separation zones may be utilized in which liquid from both is sent to a stabilization zone and the vapor from the stabilization zone is combined with a stream prior to the stream entering the second separation zone.

What is claimed is: 
     
       1. A method for the recovery of a benzene rich liquid stream and a light ends vapor stream in a xylene isomerization process from a feedstock, the method comprising:
 passing a feedstock into a deheptanizer in which the feedstock is separated into a deheptanizer vapor phase and a deheptanizer liquid phase, the deheptanizer vapor phase containing hydrocarbons with seven carbon atoms or less, and the deheptanizer liquid phase containing hydrocarbons with eight carbon atoms or more; 
 passing the deheptanizer vapor phase from the deheptanizer to a first separation zone; 
 separating the deheptanizer vapor phase in the first separation zone into a first liquid phase and a first vapor phase; 
 passing the first liquid phase from the first separation zone to a stabilization zone; 
 passing the first vapor phase from the first separation zone to a compression zone in which the first vapor phase is compressed to provide a compressed vapor phase; 
 passing the compressed vapor phase from the compression zone to a second separation zone; 
 separating the compressed vapor phase into a second liquid phase and a second vapor phase in the second separation zone, the second vapor phase being a light ends vapor stream; 
 recovering the light ends vapor stream; 
 passing the second liquid phase to the stabilization zone; 
 separating the first liquid phase and the second liquid phase in the stabilization zone into a recycle vapor phase and a benzene rich liquid stream; 
 recovering the benzene rich liquid stream; and, 
 passing the recycle vapor phase to the second separation zone, wherein the recycle vapor phase is cooled prior to entering the second separation zone. 
 
     
     
       2. The method of  claim 1  further comprising:
 passing a portion of the first liquid phase to the deheptanizer. 
 
     
     
       3. The method of  claim 1  further comprising:
 passing a benzene rich stream from an aromatic transalkylation unit to the stabilization zone. 
 
     
     
       4. The method of  claim 1  further comprising:
 passing the benzene rich liquid stream to an extraction zone to recover a benzene stream. 
 
     
     
       5. The method of  claim 1  further comprising:
 passing the benzene rich liquid stream to storage. 
 
     
     
       6. The method of  claim 1  further comprising:
 compressing the deheptanizer vapor stream before the deheptanizer vapor stream enters the first separation zone. 
 
     
     
       7. The method of  claim 6  wherein a temperature of the first separation zone is between approximately 32° C. to 149° C. 
     
     
       8. The method of  claim 7  wherein a temperature of the second separation zone is between approximately 10° C. to 149° C. 
     
     
       9. The method of  claim 1  wherein a temperature of the first separation zone is between approximately 10° C. to 149° C. and a temperature of the second separation zone is between approximately 10° C. to 149° C. 
     
     
       10. A method tier the recovery of a benzene rich liquid stream and a light ends vapor stream in a xylene isomerization process from a feedstock, the method comprising:
 passing a feedstock into a distillation column in which the feedstock is separated into a distillation vapor and a distillation liquid, the distillation vapor containing mostly hydrocarbons with seven carbon atoms or less; 
 condensing the distillation vapor; 
 separating the distillation vapor into a first liquid phase and a first vapor phase; 
 passing the first liquid phase to a stabilization zone; 
 compressing the first vapor phase into a compressed vapor phase; 
 separating the compressed vapor phase into a second liquid phase and a second vapor phase, the second vapor phase being a light ends vapor stream; 
 recovering the light ends vapor stream; 
 passing the second liquid phase to the stabilization zone; 
 separating the first liquid phase and the second liquid phase in the stabilization zone into a recycle vapor stream and a benzene rich liquid stream; 
 recovering the benzene rich liquid stream; and, 
 combining the recycle vapor stream with the compressed vapor phase. 
 
     
     
       11. The method of  claim 10  wherein a temperature of the first liquid phase is between approximately 32° C. to 149° C. 
     
     
       12. The method of  claim 11  wherein a temperature of the compressed vapor phase is between approximately 10° C. to 149° C. 
     
     
       13. The method of  claim 10  further comprising:
 passing a portion of the first liquid phase to the distillation column. 
 
     
     
       14. The method of  claim 10  further comprising:
 passing a benzene rich stream from an aromatic transalkylation unit to the stabilization zone. 
 
     
     
       15. The method of  claim 10  further comprising:
 passing the benzene rich liquid stream to an extraction zone to recover a benzene stream. 
 
     
     
       16. The method of  claim 10  further comprising:
 passing the benzene rich liquid stream to storage. 
 
     
     
       17. A method for the recovery of a benzene rich liquid stream and a light ends vapor stream in a xylene isomerization process from a feedstock, the method comprising:
 passing a feedstock into a separation zone in which the feedstock is separated into a vapor stream and a liquid stream, the vapor stream containing mostly hydrocarbons with seven carbon atoms or less, the liquid stream comprising xylene; 
 condensing the vapor stream; 
 separating the vapor stream into a first liquid phase and a first vapor phase; 
 passing the first liquid phase to a stabilization zone; 
 compressing the first vapor phase into a compressed vapor phase; 
 separating the compressed vapor phase into a second liquid phase and a second vapor phase, the second vapor phase being a light ends vapor stream; 
 recovering the light ends vapor stream; 
 passing the second liquid phase to the stabilization zone; 
 separating the first liquid phase and the second liquid phase in the stabilization zone into a recycle vapor stream and a benzene rich liquid stream; and, 
 recovering the benzene rich liquid stream. 
 
     
     
       18. The method of  claim 17  wherein a temperature of the first liquid phase is between approximately 32° C. to 149° C. 
     
     
       19. The method of  claim 18  further comprising:
 combining the recycle vapor stream with the compressed vapor phase to create a recycle loop. 
 
     
     
       20. The method of  claim 11  wherein a temperature of the compressed vapor phase is between approximately 10° C. to 149° C.